The premise of Stephen Belber's new play Don't Go Gentle, which just opened at the Lucille Lortel Theatre in an MCC Theater production, is one loaded with dazzling promise. A judge who spent decades handing down harsh sentences acquires, in his waning years, a new compassion when he gets to know a perpetrator for whom the phrase "extenuating circumstances" might as well have been coined. So driven is he to make amends for his past that he even pursues his new cause at the expense of his own children. There's no shortage of dramatic meat to be found in this setup, but the follow-through leaves you more than a little malnourished.

After Belber introduces the one-time Second Circuit judge Lawrence (Michael Cristofer), the young black mother named Tanya (Angela Lewis) he's been tasked with helping recover from a mistaken felony drug conviction, her 16-year-old son Rasheed (Maxx Brawer), and Lawrence's in-their-thirties, out-of-the-nest son and daughter Ben and Amelia (David Wilson Barnes and Jennifer Mudge), he lunges for the political jugular and misses by a meter. What functions, and even excels, as an exploration of one person's awakening sense of retribution falls flat when seen through the broader, baser lens of its intended indictment.

Lawrence is a die-hard Republican whom Belber paints as not just emptily callous for his treatment of the accused criminals who came before him, but also a raging hypocrite: He was routinely willing to pull strings to keep Ben out of prison for selling drugs, all the while sending up the river strangers who'd done far less. His offering Tanya and Rasheed a free place to stay in exchange for Tanya's helping him medically (a complex series of medications and regular doctor visits keep his days filled and his kids exasperated) is seen by some for its disquieting racial overtones, and others as charity that does everyone involved more harm than good.

The real reason for this behavior is uttered only once, but with profound implications: "social justice." Lawrence's conversion leads him to want to atone for all of his previous misdeeds, to the point that he modifies the trust on his house so that upon his death it will pass to Tanya rather than Ben and Amelia. This sets off a firestorm, of course, that leaves Amelia dumbstruck and Ben spinning off the wagon, but that is the perfectly logical continuation of events of a man so hollow he can't even properly care about anyone once he's finally "turned around."

Except for a paper-thin thread suggesting Amelia and Ben drift (slightly) further right as Lawrence corrects to the left, Don't Go Gentle unfolds as theatrically flaccid rather than as electrifying as its underlying ideas suggest is possible. The apparent contention that Lawrence's consistently despicable actions stem from his political affiliation undercuts the far more fascinating (and psychologically nuanced) notion, advanced at first but eventually swept away, that Lawrence didn't apply justice equally or appropriately. Connecting it to his politics transforms the play into a far less compelling — and, to some potential audience members, borderline insulting — diatribe that mutes too many of the real stresses weighing down this group of people.

When these are allowed to filter to the surface, the play spins forward much more effortlessly. Director Lucie Tiberghien stages with care, if rarely effusion, but Barnes, Brawer, and Mudge go much further. Each taps into the anguish foisted on their character by his or her parents, and then refashions it into something recognizable and moving. Mudge stands out for her ability to communicate epic feelings with few or no words; she barely speaks when her inheritance is stripped from her, apparently for Ben's transgressions, but the subtle deflation of trust visible behind her eyes tells you everything you need to know about what she's experiencing. But Barnes's depiction of Ben's slow descent back into the hell he thought he'd escaped and the way Brawer constantly wavers between Rasheed's hope and pride are just as crucial to what success the play enjoys.

Lewis, lost in a role that's more plot device than person, has trouble defining Tanya beyond her normal whining tendencies, not conveying the desperation that should be powering her every choice. Cristofer is hopeless as Lawrence, through no fault of his own: Given nothing concrete, let alone believable, to play, he delivers his every line as though it's confined in a vacuum of self-loathing from which nothing can escape.

To that extent, Lawrence is, however obliquely, tapping into the spirit of the Dylan Thomas poem that inspired the play's title: fighting a futile battle against an invisible force. It's easy to see how Thomas's work could inspire Belber, with its exhortations to live every remaining moment as though it's all that matters — because it ultimately is. But the work's ominous undertones undercut what should be a passionate and powerful dissection of life in its last moments. Is being a Republican, a Democrat, or a member of any other American political party really a sin to atone for? Don't Go Gentle suggests no less and, sadly, no more.